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1 // Copyright 2015 The Chromium Authors. All rights reserved. | 1 // Copyright 2015 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #ifndef CC_RESOURCES_TEXTURE_COMPRESSOR_ETC1_H_ | 5 #ifndef CC_RESOURCES_TEXTURE_COMPRESSOR_ETC1_H_ |
6 #define CC_RESOURCES_TEXTURE_COMPRESSOR_ETC1_H_ | 6 #define CC_RESOURCES_TEXTURE_COMPRESSOR_ETC1_H_ |
7 | 7 |
8 #include "cc/resources/texture_compressor.h" | 8 #include "cc/resources/texture_compressor.h" |
9 | 9 |
10 #include "base/compiler_specific.h" | |
11 #include "base/logging.h" | |
12 | |
13 namespace cc { | |
14 | |
15 template <typename T> | |
16 inline T clamp(T val, T min, T max) { | |
17 return val < min ? min : (val > max ? max : val); | |
18 } | |
19 | |
20 inline uint8_t round_to_5_bits(float val) { | |
21 return clamp<uint8_t>(val * 31.0f / 255.0f + 0.5f, 0, 31); | |
22 } | |
23 | |
24 inline uint8_t round_to_4_bits(float val) { | |
25 return clamp<uint8_t>(val * 15.0f / 255.0f + 0.5f, 0, 15); | |
26 } | |
27 | |
28 union Color { | |
29 struct BgraColorType { | |
30 uint8_t b; | |
31 uint8_t g; | |
32 uint8_t r; | |
33 uint8_t a; | |
34 } channels; | |
35 uint8_t components[4]; | |
36 uint32_t bits; | |
37 }; | |
38 | |
39 // Codeword tables. | |
40 // See: Table 3.17.2 | |
41 ALIGNAS(16) static const int16_t g_codeword_tables[8][4] = { | |
42 {-8, -2, 2, 8}, | |
43 {-17, -5, 5, 17}, | |
44 {-29, -9, 9, 29}, | |
45 {-42, -13, 13, 42}, | |
46 {-60, -18, 18, 60}, | |
47 {-80, -24, 24, 80}, | |
48 {-106, -33, 33, 106}, | |
49 {-183, -47, 47, 183}}; | |
50 | |
51 // Maps modifier indices to pixel index values. | |
52 // See: Table 3.17.3 | |
53 static const uint8_t g_mod_to_pix[4] = {3, 2, 0, 1}; | |
54 | |
55 // The ETC1 specification index texels as follows: | |
56 // [a][e][i][m] [ 0][ 4][ 8][12] | |
57 // [b][f][j][n] <-> [ 1][ 5][ 9][13] | |
58 // [c][g][k][o] [ 2][ 6][10][14] | |
59 // [d][h][l][p] [ 3][ 7][11][15] | |
60 | |
61 // [ 0][ 1][ 2][ 3] [ 0][ 4][ 4][ 5] | |
62 // [ 4][ 5][ 6][ 7] <-> [ 8][ 9][12][13] | |
63 // [ 8][ 9][10][11] [ 2][ 3][ 6][ 7] | |
64 // [12][13][14][15] [10][11][14][15] | |
65 | |
66 // However, when extracting sub blocks from BGRA data the natural array | |
67 // indexing order ends up different: | |
68 // vertical0: [a][e][b][f] horizontal0: [a][e][i][m] | |
69 // [c][g][d][h] [b][f][j][n] | |
70 // vertical1: [i][m][j][n] horizontal1: [c][g][k][o] | |
71 // [k][o][l][p] [d][h][l][p] | |
72 | |
73 // In order to translate from the natural array indices in a sub block to the | |
74 // indices (number) used by specification and hardware we use this table. | |
75 static const uint8_t g_idx_to_num[4][8] = { | |
76 {0, 4, 1, 5, 2, 6, 3, 7}, // Vertical block 0. | |
77 {8, 12, 9, 13, 10, 14, 11, 15}, // Vertical block 1. | |
78 {0, 4, 8, 12, 1, 5, 9, 13}, // Horizontal block 0. | |
79 {2, 6, 10, 14, 3, 7, 11, 15} // Horizontal block 1. | |
80 }; | |
81 | |
82 inline void WriteColors444(uint8_t* block, | |
83 const Color& color0, | |
84 const Color& color1) { | |
85 // for BGRA textures | |
86 block[0] = (color0.channels.r & 0xf0) | (color1.channels.r >> 4); | |
87 block[1] = (color0.channels.g & 0xf0) | (color1.channels.g >> 4); | |
88 block[2] = (color0.channels.b & 0xf0) | (color1.channels.b >> 4); | |
89 } | |
90 | |
91 inline void WriteColors555(uint8_t* block, | |
92 const Color& color0, | |
93 const Color& color1) { | |
94 // Table for conversion to 3-bit two complement format. | |
95 static const uint8_t two_compl_trans_table[8] = { | |
96 4, // -4 (100b) | |
97 5, // -3 (101b) | |
98 6, // -2 (110b) | |
99 7, // -1 (111b) | |
100 0, // 0 (000b) | |
101 1, // 1 (001b) | |
102 2, // 2 (010b) | |
103 3, // 3 (011b) | |
104 }; | |
105 | |
106 int16_t delta_r = | |
107 static_cast<int16_t>(color1.channels.r >> 3) - (color0.channels.r >> 3); | |
108 int16_t delta_g = | |
109 static_cast<int16_t>(color1.channels.g >> 3) - (color0.channels.g >> 3); | |
110 int16_t delta_b = | |
111 static_cast<int16_t>(color1.channels.b >> 3) - (color0.channels.b >> 3); | |
112 DCHECK_GE(delta_r, -4); | |
113 DCHECK_LE(delta_r, 3); | |
114 DCHECK_GE(delta_g, -4); | |
115 DCHECK_LE(delta_g, 3); | |
116 DCHECK_GE(delta_b, -4); | |
117 DCHECK_LE(delta_b, 3); | |
118 | |
119 // For BGRA textures | |
120 block[0] = (color0.channels.r & 0xf8) | two_compl_trans_table[delta_r + 4]; | |
121 block[1] = (color0.channels.g & 0xf8) | two_compl_trans_table[delta_g + 4]; | |
122 block[2] = (color0.channels.b & 0xf8) | two_compl_trans_table[delta_b + 4]; | |
123 } | |
124 | |
125 inline void WriteCodewordTable(uint8_t* block, | |
126 uint8_t sub_block_id, | |
127 uint8_t table) { | |
128 DCHECK_LT(sub_block_id, 2); | |
129 DCHECK_LT(table, 8); | |
130 | |
131 uint8_t shift = (2 + (3 - sub_block_id * 3)); | |
132 block[3] &= ~(0x07 << shift); | |
133 block[3] |= table << shift; | |
134 } | |
135 | |
136 inline void WritePixelData(uint8_t* block, uint32_t pixel_data) { | |
137 block[4] |= pixel_data >> 24; | |
138 block[5] |= (pixel_data >> 16) & 0xff; | |
139 block[6] |= (pixel_data >> 8) & 0xff; | |
140 block[7] |= pixel_data & 0xff; | |
141 } | |
142 | |
143 inline void WriteFlip(uint8_t* block, bool flip) { | |
144 block[3] &= ~0x01; | |
145 block[3] |= static_cast<uint8_t>(flip); | |
146 } | |
147 | |
148 inline void WriteDiff(uint8_t* block, bool diff) { | |
149 block[3] &= ~0x02; | |
150 block[3] |= static_cast<uint8_t>(diff) << 1; | |
151 } | |
152 | |
153 // Compress and rounds BGR888 into BGR444. The resulting BGR444 color is | |
154 // expanded to BGR888 as it would be in hardware after decompression. The | |
155 // actual 444-bit data is available in the four most significant bits of each | |
156 // channel. | |
157 inline Color MakeColor444(const float* bgr) { | |
158 uint8_t b4 = round_to_4_bits(bgr[0]); | |
159 uint8_t g4 = round_to_4_bits(bgr[1]); | |
160 uint8_t r4 = round_to_4_bits(bgr[2]); | |
161 Color bgr444; | |
162 bgr444.channels.b = (b4 << 4) | b4; | |
163 bgr444.channels.g = (g4 << 4) | g4; | |
164 bgr444.channels.r = (r4 << 4) | r4; | |
165 // added to distinguish between expanded 555 and 444 colors | |
166 bgr444.channels.a = 0x44; | |
167 return bgr444; | |
168 } | |
169 | |
170 // Compress and rounds BGR888 into BGR555. The resulting BGR555 color is | |
171 // expanded to BGR888 as it would be in hardware after decompression. The | |
172 // actual 555-bit data is available in the five most significant bits of each | |
173 // channel. | |
174 inline Color MakeColor555(const float* bgr) { | |
175 uint8_t b5 = round_to_5_bits(bgr[0]); | |
176 uint8_t g5 = round_to_5_bits(bgr[1]); | |
177 uint8_t r5 = round_to_5_bits(bgr[2]); | |
178 Color bgr555; | |
179 bgr555.channels.b = (b5 << 3) | (b5 >> 2); | |
180 bgr555.channels.g = (g5 << 3) | (g5 >> 2); | |
181 bgr555.channels.r = (r5 << 3) | (r5 >> 2); | |
182 // added to distinguish between expanded 555 and 444 colors | |
183 bgr555.channels.a = 0x55; | |
184 return bgr555; | |
185 } | |
186 | |
187 } // namespace cc | |
reveman
2015/05/07 14:24:35
nit: remove this and "namespace cc {" two lines be
radu.velea
2015/05/07 15:53:45
Done.
| |
188 | |
10 namespace cc { | 189 namespace cc { |
11 | 190 |
12 class CC_EXPORT TextureCompressorETC1 : public TextureCompressor { | 191 class CC_EXPORT TextureCompressorETC1 : public TextureCompressor { |
13 public: | 192 public: |
14 TextureCompressorETC1() {} | 193 TextureCompressorETC1() {} |
15 | 194 |
16 // Compress a texture using ETC1. Note that the |quality| parameter is | 195 // Compress a texture using ETC1. Note that the |quality| parameter is |
17 // ignored. The current implementation does not support different quality | 196 // ignored. The current implementation does not support different quality |
18 // settings. | 197 // settings. |
19 void Compress(const uint8_t* src, | 198 void Compress(const uint8_t* src, |
20 uint8_t* dst, | 199 uint8_t* dst, |
21 int width, | 200 int width, |
22 int height, | 201 int height, |
23 Quality quality) override; | 202 Quality quality) override; |
24 | 203 |
25 private: | 204 private: |
26 DISALLOW_COPY_AND_ASSIGN(TextureCompressorETC1); | 205 DISALLOW_COPY_AND_ASSIGN(TextureCompressorETC1); |
27 }; | 206 }; |
28 | 207 |
29 } // namespace cc | 208 } // namespace cc |
30 | 209 |
31 #endif // CC_RESOURCES_TEXTURE_COMPRESSOR_ETC1_H_ | 210 #endif // CC_RESOURCES_TEXTURE_COMPRESSOR_ETC1_H_ |
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